Confidence among Silicon Valley VCs in business conditions ahead rose modestly in the final three months of 2012 for the second quarter in a row, suggesting rising optimism among investors.

Yet it remains below the levels it reached in 2006 and 2007 prior to the economic recession and the downturn of the past several years.

The Silicon Valley Venture Capital Confidence Index rose to 3.63 in the fourth quarter, up from 3.53 in the third quarter. The index, calculated by University of San Francisco professor Mark Cannice and based on a survey of 23 area venture capitalists, uses a five-point scale, with 5 being high confidence.

Investors continue to be jazzed by technology trends involving big data and mobile computing, but restrained by the ongoing budget debates in Washington and the generally slow world economic conditions.